Interrelated power delivery controls – including engine control – Transmission control – Transmission controlled by engine
Patent
1991-04-25
1995-05-23
Wright, Dirk
Interrelated power delivery controls, including engine control
Transmission control
Transmission controlled by engine
477158, B60K 4110
Patent
active
054176263
DESCRIPTION:
BRIEF SUMMARY
The invention concerns an electronic-hydraulic control mechanism of an automatically shifting motorcar transmission including, for shifting of specific speed levels, hydraulically engageable and disengageable friction clutches or brakes, a control valve being coordinated with each of their actuation devices, a main pressure valve that regulates the pressure level in a main pressure system and a control unit designed as microprocessor which, depending on operation parameters of the motorcar transmission and of a drive engine, can adjust the electronically actuated solenoid valves and pressure-control valves that control the actuation devices in the same manner whether shifting and/or program control.
An electronic-hydraulic mechanism of an automatically shifting motorcar transmission of the above mentioned kind has been disclosed in German Patent 29 45 315. This control system has two electromagnetically actuated pressure-control valves that regulate the buildup and reduction of pressure on the actuation devices of the friction clutches or brakes, the pressure-control valves in the main pressure system being inserted after the main pressure valve. Said pressure-regulating valves take care of a regulated buildup or reduction of pressure in the actuation device of the friction clutch or brake to be engaged or disengaged at a given time. For this purpose, a valve unit is coordinated with each actuation device consisting of an electro-magnetically actuated shift valve and two reversing valves actuated by the working pressure. At any given time during the engaging or disengaging operation, pressurized fluid is fed to the actuation device or drained from the actuation device via the corresponding pressure-control valve by means of the reverse valves. After this shifting operation with regulated buildup or reduction of pressure in the actuation devices, the reverse valves reach a position in which, bypassing the pressure-control valves, they create a connection between the respective actuation device and the main pressure system or a tank connection since there is coordinated with each actuation device a corresponding valve unit consisting of shift valve and reverse valves, said electronic-hydraulic mechanism of an automatically shifting motorcar transmission has the disadvantage of an elevated construction cost.
Therefore, the invention is based on the problem of reducing, in an electronic-hydraulic control mechanism of an automatically shifting motorcar transmission, the construction cost for a regulated pressurization and a regulated pressure reduction in the actuation devices of the friction clutches or brakes.
In an electronic-hydraulic mechanism of the kind mentioned above, this problem is solved by the fact that the pressure-control valves are situated in a first control system of reduced pressure compared to the main pressure system and through which they act with pilot control upon the control valves and the main pressure valve, and the solenoid valves are situated in a second control system also of reduced pressure as compared to the main pressure system, said solenoid valves acting with pilot control upon shift valves which control the supply of pressurized fluid from the main pressure system to the control valves and a reverse locking valve. All shifting operations and the adjustment of the pressure level in the main pressure system are thus carried out with regulation. Aside from the fact that a control valve is coordinated with each actuation device, the remaining hydraulic structural elements, such as solenoid valves and shift valves, can assume multiple functions.
Other advantageous embodiments of the invention are described in claims 2 to 11. According to claim 2 a pressure-control valve, which controls a discharge proportionally to the current, is situated in a control line of the first control system through which the main pressure valve, depending on the engine torque, can be relieved of pressure on its spring-loaded face end in a manner such that, by means of the main pressure valve, the requi
REFERENCES:
patent: 4658705 (1987-04-01), Fujio
patent: 4691594 (1987-09-01), Taga et al.
patent: 5078028 (1992-01-01), Ishikawa et al.
patent: 5107723 (1992-04-01), Yamashita et al.
patent: 5289739 (1994-03-01), Muscaro et al.
Wright Dirk
Zahnradfabrik Friedrichshafen AG
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